The "black boxes" aka the data recorders are in the tail of the aircraft, because this is best place to keep them. The rebels say they don't have the data recorders, they probably do have them, they might be rebels but they would know enought to know possession of the data recorders would give them bargaining power. For the moment they have the wreckage, the remains, the luggage and all the passports and identification, and the data recorders, all we can do is try to reason with them.
I don't think all the rebels are dangerous and unreasonable, obviously some of them are out of control, hopefully someone can reason with them or their leaders.
